The Ambient clock combines a typical clock interface with the event data from your google calendar so you can see a simple view of your scheduled time vs. free time at a glance. The background color changes if you have up-coming events as a additional identifier.
With a quick glance you can determine:

How long until my next event?

What time is my first event?

What time does my last event end?

What is my ratio of free time vs. scheduled time?

Additionally, if your google event has location information added to it, the Ambient clock will estimate your commute time to that event and display it as dots preceding the event.

None of these physical clocks are in production yet, but you can get a google homepage version. They claim that the physical version would only need AAA batterys and connect via Ambiant's nationwide wireless network.